Beneath the waters of the Ganga lies an invisible threat that scientists are only beginning to understand. A study by researchers from Europe and India warns that current scientific methods detect only 1 per cent of per- and polyfluoroalkyl substances (PFAS), or “forever chemicals”, in the riverbed. This raises concerns about the scale of pollution in a river that supports 7 per cent of the global population.
PFAS are synthetic compounds composed primarily of carbon and fluorine, used in cookware, clothes and food packaging. The strong carbon-fluorine bond allows PFAS to persist in rivers, soils and even human blood long after the products are discarded and broken down.
Exposure to PFAS is associated with cancer, thyroid dysfunction, immune suppression, reproductive and developmental disorders. The study, published in the journal Environment International in January, aimed to analyse PFAS in sediment samples from 14 locations along a 58-km stretch of the Ganga between Rishikesh and Roorkee in Uttarakhand (see ‘Contaminated stretch’).
The team used four conventional tests, including targeted and non-targeted screening through liquid chromatography tandem mass spectrometry (LC-MS/MS), a method used globally, to measure the total amount of extractable organic fluorine (EOF) in the sediment samples. This amount was compared with the fluorine content in PFAS that can be identified. The results showed a staggering mismatch in numbers or a “fluorine mass balance,” says Viktoria Müller, postdoctoral researcher at the University of Graz, Austria, and lead author of the study.
Conventional targeted analysis identified only 16 known PFAS in the samples, Müller tells Down To Earth (DTE). Concentrations of the known compounds were 0.02-5.3 nanograms (ng) per gram of sediment, while total EOF concentrations were 180-780 ng per gram—in some downstream sites, the amount was nearly five times higher than upstream sites near Rishikesh. This indicated unidentified fluorinated chemicals in the sediments.
The findings indicate several points of concern: first, that modern testing methods are unable to accurately identify a majority of the PFAS categories detected in the Ganga. This poses problems in finding the source of the ...
This article was originally published in the July 1-15, 2026 print edition of Down To Earth, which also features an exclusive interview with a scientist studying PFAS contamination in the Ganga